The invention relates generally to electrical contacts and, more particularly, to a wrapped electrical contact for a socket connector.
Competition and market demands have continued the trends toward faster, higher performance electrical systems, particularly with regard to computer systems. Along with the development of surface mount technology in the design of printed circuit boards, higher density electrical circuits, including higher density interconnect components have been developed to meet the increasing demand for higher performance electrical systems.
As is well understood in the art, surface mountable packaging allows for the connection of the package to pads on the surface of the circuit board rather than by contacts or pins soldered in plated holes going through the circuit board. As used herein, the term “package” shall refer to a chip carrying module that is to be mounted to a circuit board. Surface mount technology allows for an increased component density on a circuit board, thereby saving space on the circuit board.
Area array socket connectors have evolved, along with surface mount technology, as one high density interconnect methodology. One significant application of this technology, for example, is the land grid array (LGA) socket connector that is used with an LGA package. One major advantage of the LGA package lies in its durability. The LGA package is not easily damaged during the installation or removal process or by handling generally. At least some of the other integrated circuit (IC) packages, such as a pin grid array (PGA) package, have a standardized layout, or form factor, for contact leads or pins on the package. These contact leads are somewhat fragile and can be damaged if not handled properly. By contrast, with an LGA package, there is nothing protruding from the package that can be bent or otherwise damaged during normal handling.
While the LGA package is quite durable, the LGA socket is somewhat less so. In the LGA socket, the contacts are partially exposed. To minimize the possibility of damage to the contacts, the LGA socket is designed for loading and unloading of the package in a vertical direction, e.g. normal to the circuit board.
One potential problem with the LGA form factor lies in the fact that ceramic surfaces on electronic packages are not perfectly flat. In the case of an LGA package, the ceramic surfaces of the mating face is also not perfectly flat, so that the LGA socket must provide enough compliance in the loading direction to provide tolerance for the unevenness of the package surface. Package manufacturers, naturally, would like this tolerance to be as great as possible, while socket manufacturers would like to keep it small.
In the typical LGA socket, the contacts have flexible cantilevered beams that mate with the LGA package. These beams are deflected as the socket moves through its compliance range to accommodate surface variations in the LGA package. Additionally, any unevenness in the circuit board mounting surface is also dealt with through the compliance of the socket and the flexibility of the contacts. As the contact beams are deflected however, they overlay each other which can result in electrical coupling between the contacts which introduces noise into the system.
A need exists for contacts that can accommodate the compliance of the LGA socket without introducing noise into electronic systems.